Air Pressure

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Air Pressure
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Properties of Air

• Air has mass
• Density
• Pressure

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Density

• The amount of mass in a given volume of air
• Density Mass Volume
• More molecules means higher density

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Air Pressure

• The force pushing on an area or surface
• The denser the air, the greater the air pressure
• The result of the weight of a column of air
  pushing down on an area

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Measuring Air Pressure

• Barometer an instrument that is used to measure
  changes in air pressure
• Mercury barometer glass tube open at the
  bottom, partially filled with mercury
• Aneroid barometer airtight metal chamber,
  without liquid (portable and more practical)

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Units of Air Pressure

• Usually measured in millibars

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Increasing Altitude

• Altitude elevation distance above sea-level
• Air pressure DECREASES as altitude INCREASES
• Air pressure INCREASES as altitude DECREASES
• As air pressure DECREASES, so does density

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Altitude Affects Density

• If you were at the top of a mountainhard to
  breathe
• This is because the air pressure decreases.so,
  air is less dense, which means there are fewer
  oxygen molecules to breathe per cubic meter of
  airso, with each breath you are taking in less
  oxygen

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Page 24 Cars and Clean Air

• Identify the Problem
• Analyze the Options
• Find a Solution